To follow up on my son's wagon, He is using the pump from a 97 Ram. We made brackets so it could be mounted on the modern Hemi (yes, the pumps and brackets are different between a 5.9 and a 5.7).
This pump has been on the car for about 3 years. He did something to reduce the pump pressure so it matches the pressure output of the original 57 pump. I think he used a bypass regulator that allows you to adjust the pressure. What he doesn't like is the feedback the original power steering for this wagon gives him, even with sway bars and a completely rebuild suspension.

Lmopar69, I will be looking forward to your findings with the van chassis. Gene